(a) Field of the Invention
This invention in its broadest aspect, relates to inhibitors of metabolic pathways. In particular the invention relates to novel compounds of Formula I which are inhibitors of leukotriene D.sub.4 (LTD.sub.4) and therefore useful to prevent or alleviate the symptoms or conditions associated with LTD.sub.4 such as allergic reactions and inflammatory conditions.
LTD.sub.4 is a product of the 5-lipoxygenase pathway and is the major active constituent of slow reacting substance of anaphylaxis (SRS-A) in humans and guinea pigs, Lewis et al. Nature USA, 293: 103-108, (1981). It is a potent bronchoconstrictor that is released during allergic reactions. Because antihistamines are ineffective in the management of asthma it is believed that SRS-A mediates bronchoconstriction resulting from an allergic attack, LTD.sub.4 is also a potent inducer of vascular permeability and it also may be involved in other inflammatory conditions such as rheumatoid arthritis, Geller, J., et al., J. Clin. Endocrinol. Metalb. 43: 686-688, (1976).
(b) Information Disclosure
Appleton et al., J. Med. Chem. 20, 371-379 (1977) discloses a series of chromone-2-carboxylic acids which are antagonists of SRS-A. Specifically sodium 7-[3-(4-acetyl-3-hydroxy-2-propylphenoxy)-2-hydroxypropoxy]-4-oxo-8-propyl -4H1-benzopyran-2-carboxylate (FPL 55712), appears to be the first reported specific antagonist of SRS-A and LTD.sub.4.